One known form of display device is a self-light-emitting type display device such as an organic electroluminescence display device. Electroluminescence will be abbreviated EL herein. In an organic EL display device, light emitted from a light-emitting layer progresses in all directions, and a part of the light is totally reflected by the difference in refractive indexes between the light-emitting element and an external space (air). A large amount of the light totally reflected at the boundary between the light-emitting element and air is bound within the light-emitting element, and is not extracted to the external space. For example, if the refractive index of the external space is 1.8, of the light emitted from the light-emitting layer, approximately 20% is extracted to the external space, and the remaining approximately 80% is bounded within the light-emitting layer. In this manner, a conventional organic EL device has the problem of a low light usage efficiency.
In Patent Document 1 noted below, an organic EL display device that has a carrier substrate, an organic EL element provided on the carrier substrate, and a light-reflecting layer that reflects light emitted from the organic EL element is disclosed. In the organic EL display device, a recess that includes an inclined surface along the outer edge of an organic light-emitting layer is provided in the light-reflecting layer. Light emitted from the light-emitting layer, after being reflected at the inclined surface of the recess, returns toward the organic EL element once again. This constitution is described as preventing image quality deterioration by, for example, bleeding, and improvement in light usage efficiency.
In general, the light emission spectrum of a light-emitting material tends to be a broad distribution over a wide wavelength range. For that reason, if high color purity is demanded, it is not possible to obtain the desired color purity with the intrinsic spectrum of a light-emitting material. A method that has been proposed for increasing the color purity is a so-called microcavity structure, in which light emitted from a light-emitting layer is caused to multiply reflect and resonate between a pair of reflective layers. When light is multiply reflected and resonates between a pair of reflective layers, the effect is achieved of the light emission spectrum in the vicinity of the resonant wavelength becoming steep, the light intensity at the peak wavelength increasing and the color purity increasing. For example, Patent Document 2 noted below discloses an organic light-emitting display device having a lower electric, an upper electrode, and an alternately stacked dielectric film, with a microcavity structure formed by the alternately stacked dielectric film and the lower electrode.